Electric-motor starter.



T. A. MELVILLEL ELECTRIC MOTOR STARTER.

APPLICATION FILED OCT-25,1916.

1,237,080. Patented Aug. 14,1917.

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ELECTRIC MOTOR STARTER.

APPLICATION FILED ocr.25.19;'e. 1,237,080. Patented Au 14, 1917.

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ELECTRIC MOTOR STARTER.

APPLICATION FILED dcr.2s.191e. 1,237,080, Patented Aug. 14, 1917.

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. s Q I 5 i OQO 'i 23 g o O O 5 Li C snow Mien UNITED STATES PATENT OFFICE.

THOMAS A. MELVILLE, OF FARGO, NORTH DAKOTA.

ELECTRIC-FIOTOR STARTER.

Application filedOctober 25, 1916.

To all whom it may concern:

Be it known that THOMAS A. MELVILLE, a citizen of the United States, residing at Fargo, in the county of Cass and State of North Dakota, has invented new and useful Improvements in Electric-Motor Starters, of which the following is a specification.

This invention relates to a combined rheostat and circuit breaker so designed as to incorporate the functions of the circuit breaker and the rheostat in a unitary article.

lVith the usual starting device or rheostat in use consisting of a separate switch or circuit breaker and rheostat the resistance cut out arm of the rheostat will not return to normal or dead point of the rhcostat until several seconds after the motor has come to a full stop due to residual magnetism in the holding magnet. In the meantime. all resistance is cut out of circuit and should the switch of the circuit be again closed, full current will be directed to the motor which will result either in the fuses being blown out or serious injury to the armature of the motor. In addition, after the rheostat has been used for a considerable length of time, the holding magnet will become stronger due to permanent magnetism, and the return spring of the resistance cut out arm weaker, resulting in the arm remaining in engagement with the holding magnet for some length of time after the current has been cut off. In this latter case if the switch is closed without first bringing the resistance cut out arm to normal position, the fuses or motor or other translating device would be ruptured.

The primary object of the invention is to overcome the above defects by mechanism, the elements of which are so arranged as to prevent the closing of a circuit when the resistance cut out arm is in any position but normal.

An object of the invention is to so construct the cooperating elements that the switch controlling the circuit may be opened at any point in the travel of the resistance cut out arm of the rheostat, but prevented from again closing the switch in any position but normal of the resistance cut out arm.

Another object of the invention is to so relate the elements that a unitary article will be capable of opening and closing the circuit and varying the resistance of the cir- Specification of Letters Patent.

Patented Aug. 14, 1917.

Serial No. 127,663.

cuit, so as to minimize the amount of space occupied and the numerous exposed wires.

Besides the above my invention is distinguished in the use of a pawl and ratchet so designed and related to the other elements as to lock the switch in open position in all positions of the resistance cut out arm except normal.

A very important feature of my invention is that certain elements of the improvement can be associated and connected to those rheostats now in use without the necessity of complicated alterations.

The invention will be better understood from the following detailed description, taken in connection with the accompanying drawings wherein a preferred embodiment is illustrated, and the features of novelty including all the above mentioned and various others will be thereinafter pointed out in the appended claims.

One practical construction and assembly with some modifications will be described and illustrated in the accompanying drawings in which Figure 1 is a front elevation of the apparatus with portions broken away showing the arm in normal position; Fig. 2 is a front elevation of the apparatus similar to Fig. 1 but with the arm thrown to the running position and in engagement with the release magnet; Fig. 3 is a sectional view on the line 33 of Fig. 1; Fig. at is a sectional view on the line H of Fig. 1'; Fig. 5 is a detail view of the locking device; Fig. 6 is a perspective view of the arcuate rack bar; Fig. 7 is a side elevation of the apparatus connected to a spaced starting box the arm of which is shown in the off position; Fig. 8 is a modification of the locking device shown in Fig. 5; and Fig. 9 is a perspective view of the dog or pawl.

Referring more particularly to Figs. 1 to S inclusive, the numeral 1 designates a base of insulating material supporting the usual binding posts 2, contacts 3 to which any usual type of resistance element is connected and a holding magnet 4, the outline of construction being that commonly employed.

Also mounted on the base 1 and forming a portion of my invention is a switch having the blades 5 arranged to control the circuit that includes the resistance element. The switch as well as the fuses associated therewith are preferably inclosed in a casing 6 to conform to the requirements of the underwriters code, which casing is supported by the base 1.

Secured to the base is a bracket 7 upon which is suitably j ournaled or pivotally mounted an arm 8 which carries the contact wiper 9 that is adapted to move over and engage with the contacts 3. This arm 8 differs from the usual construction now in use, in being formed with an arcuate slot 10, and having a pin or stud 11 which is shown as projecting laterally from said arm. Secured to the arm 8 adjacent the connection with the bracket is a coil spring 12 that has its remaining extremity secured to a stud 13 so that the spring 12 may be extended under tension therebetween.

Associated with the arm 8 is a handle 14 which is provided with an opening 15 having tapering walls for the reception of the pin 11, and also with a lu 16 that is mov able in the slot 10. At thls point I wish to call attention to the fact that the pin is provided with a tapering surface cooperating with the tapering wall of the opening 15 so that the pawl and ratchet device to be de scribed later will be properly associated irrespective of the wearing action between the lug 16 and the sides of the slot 10, but I wish it to be understood that it is not absolutely necessary to use the pin as the cooperation of the lug and the walls of the slot may be utilized to move the arm and handle in unison.

From the foregoing description it will be seen that under normal conditions the arm and handle swing across the contact 3 as a unit, but should it become necessary to open the switch, the handle 14 must be moved outward in a direction away from the arm 8. To accomplish the latter result, the handle at an intermediate point is formed with an opening 17 through which passes a bolt 18 which also passes through the apertured extremity 19 of a rod 20. The rod 20 in this particular instance is rotatably mounted in the bracket 7 and may be secured to the blades 5 of the switch by any suitable means, one of which is shown by the clamps 21 in Fig. 1. Thus it will be seen that the arm and handle 14 may be moved over the contacts as a unit without transmitting movement to the rod, but should the handle 14 be moved in a direction away from the arm 8, the rod 20 will be actuated for opening the switch. The rod 20 being rotatably mounted provides for a pivotal connection with the handle 14.

I will now describe the mechanism for locking the handle against return movement when the switch has been opened until the arm 14 reaches an inoperative or ofl po-' sition. In this particular instance I have formed one extremity of the handle into an arcuate shaped rack bar 22, the teeth of which are arranged concentrically to the center of the bolt 18 relative to their length whereas in a transverse direction they are arranged concentrically to the center of the adjacent portion of the rod 20. In other words, when the handle is moved in unison with the arm, the teeth will move concentrically to the bolt 18 whereas when the handle is moved in a direction away from the arm, the teeth are moved in a direction concentrically to the center of the adjacent portion of the rod. Pivotally supported by the bracket 7 is a dog 28 that is adapted to be pressed into engagement with the teeth of the rack bar 22 by means of an expansion spring 24 housed in a tubular extension 25 mounted on the bracket. For reasons to be set forth later the dog is limited in its move ment toward the teeth by the pin 26. The rack bar 22 is of such a width as to remain in engagement with the dog in all movements of the arm away from normal, but when the arm is in normal position the rack bar moves out of engagement with the dog with the result that the handle may be free to move in a lateral direction toward or away from the arm for opening and closing the switch.

lVhen the arm is in normal position and the handle in a position to open the switch, the dog will be projected beyond the adjacent edge of the rack bar with the result that it will be impossible for the arm to move with the switch in open position and thus it will be seen that resistance cannot be cut out of the circuit when the switch is in open position. For the purpose of displacing the dog sufficiently to permit of the free movement of the rack bar, when the handle is properly associated with the arm and the switch closed, I preferably form the rack bar with a cam surface 27, as shown, which is adapted to engage the pawl and force it in a direction away from the rack bar. To complete my invention I mount upon the bracket 7 a bumper or stop member 28 that receives the impact of the arm 8 when it returns to normal or off position through the action of the spring 12. A very important feature of this bumper in connection with the bracket is that the insulat ing base is not subjected to excessive shock and as the result the life of the base is prolonged.

From the foregoing description it will be seen that the switch may be opened and closed when the arm 8 is in normal position, the arm 8 prevented from movement from normal position when the switch is opened, and the switch prevented from being closed when the resistance element as a whole or part is cut out of the circuit. Thus it will be seen that it would be impossible for a careless person to close the switch of a translating device when the resistance element as a whole or part is cut out of the circuit.

In the modified form of my invention illustrated in Figs. 7 and 8 I have shown certain of the elements so arranged as to be readily connected to a rheostat and switch now in use. This apparatus consists of a handle 28 identical in construction with relation to handle 14 with the exception that the handle does not have the pin connection 11 with the arm 30. The arm 30 is constructed the same as the arm 8 with the exception that the wiper 9 is dispensed with and a series of openings 31 substituted. The openings 31 are for the purpose of allowing an adjustable connection between the arm and one end of a two-part link 32 that has its remaining end pivotally connected with the resistance cut out arm 33 of the well known type of rheostat. The connection between the handle and the switch is the same as heretofore described with relation to the preferred form of my invention and therefore a detailed description will be eliminated.

The construction and assembly which has been described is capable of use in similar ways and purposes where a control of a circuit which includes resistance is desired, which will be obvious to those skilled in the art.

Minor changes in form, proportion and details of construction may be resorted to without departing from the spirit of the invention and the scope of the appended claims.

What I claim is:

1. The combination of a supply circuit with a rheostat having a subdivided resistance element, a two part arm for cutting out the element step by step, and means adapted to be operated by one of the parts of said arm for controlling said circuit independently of the other part.

2. The combination of a supply circuit including a switch with a starting lOOX having a resistance element, an arm to cooperate therewith and adapted to cut out the resistance step by step, said arm being formed of members capable of unitary and also independent movement, and means for con necting said switch with one of the mem' bers to permit of such independent movement for opening and closing said switch of the su )ply circuit.

3. A rheostat comprising a switch, a resistance element, an arm mounted for swinging movement for cutting out the resistance element step by step, a rotatable mounted handle guided in its movement by said arm, an element connecting said handle to the switch, and a pawl and ratchet device for said handle whereby said handle may be locked in a plurality of positions.

at. A rheostat comprising a switch, a re sistance element, an arm mounted for swinging movement for cutting out the resistance element step by step, a rotatable mounted handle guided in its movement by said arm, an element connecting said handle to the switch, said handle being provided with a series of ratchet teeth, and a dog carried by a stationary support and cooperating with the teeth for locking said handle in any of its adjustable positions.

5. A rheostat comprising a switch and resistance element, an arm movably mounted for cutting out the resistance element step by step, a rotatably mounted handle to be guided in this movement and connecting said handle to the switch, and a pawl and ratchet device for said handle to control the operation of said switch in a variety of positions.

6. In a rheostata resistance cut out arm, a knife switch, a rod connected to the blade of said switch, a handle secured. to said rod, and a connection between said handle and arm whereby the two may be moved in unison.

7. In a rheostat a resistance cut out arm, a knife switch, a rod connected to the blade of said switch, a handle secured to said rod, and a connection between said handle and arm whereby the two may be moved in uni son, said handle further having a lug and slot connection with said arm whereby said handle will be guided in a direction to actuate said rod.

8. In a rheostat a resistance cut out arm, a knife switch, a rod connected to the blade of said switch, a handle secured to said rod, a connection between said handle and arm whereby the two may be moved in unison, said handle further having a lug and slot connection with said arm whereby said handle will be guided in a direction to actuate said rod, and means for locking said rod in an actuated position.

9. In a rheostat a resistance cut out arm, a knife switch, a rod connected to the blade of said switch, a handle secured to said rod, a connection between said handle and arm whereby the two may be moved in unison, said hande further having a lug and slot connection with said arm whereby said handle will be guided in a direction to actuate said rod, and means associated with said handle whereby said handle may be locked when said rod is actuated, said means being so designed as to allow the return of the handle and rod to normal position when said arm reaches normal position.

10. In a rheostat a base, a switch mounted thereon, a bracket mounted on said base, a resistance cut out arm rotatably mounted in said bracket, a rod rotatably mounted in said bracket, and having a connection with said switch, and means associated with said arm and so connected to said rod as to be capable of two movements one in a direction with said arm and the other in a direction to operate said rod.

11. In a rheostat a base, a switch mounted thereon, a bracket mounted on said base, a resistance cut out arm rotatably mounted in said bracket, a rod rotatably mounted in said bracket, and having a connection with said switch, and means having a lug and slot connection with said arm, a pivotal con nection with said rod whereby said means and arm may be moved as a unit in one direction and said rod actuated upon movement of the. means in a direction away from said arm, and means for locking said first means when moving in a direction away from said arm.

12. In a rheostat a base, a switch mounted thereon, a bracket mounted on said base, a resistance cut out arm rotatably mounted in said bracket, a rod rotatably mounted in said bracket, and having a connection with said switch, means having a lug and slot connection with said arm, and a pivotal connection with said rod whereby said means and arm may be moved as a unit in one di rection and said rod actuated upon movement of the means in a direction away from said arm, and means for locking said first means when moving in a direction away from said arm, said last means being so designed as to unlock with said first means when said arm reaches normal position.

13. In a rheostat a pivoted resistance cut out arm, a handle having a lug and slot connection with said arm, a bracket, a control rod mounted thereon for rotation and having a pivotal connection with an intermediate portion of said handle, and locking means cooperating with one extremity of said handle and the bracket to control the movement of said rod.

14. In a rheostat a pivoted resistance cut out arm, a handle having a lug and slot connection with said arm, a control rod mounted for rotation and having a pivotal connection with an intermediate portion of said handle, said handle having one extremity formed into a rack bar, and means cooperating with said rack bar and so positioned as to allow said handle to operate said rod in any position of the arm, but to prevent return movement of the handle when the arm is in any position but normal.

15. In combination with a switch and a rheostat, an actuator comprising a pivoted arm having a pivotal connection with the resistance cut out arm of the rheostat, a handle having a connection with said switch, and guided in its movement by said arm, and means for locking said handle against a return movement upon said switch being opened until said arm reaches a predetermined position.

16. In combination with a switch and a resistance, an actuator comprising a pivoted arm having an adjustable connection with the resistance cut out arm of the rheostat, a rod connected to said switch, and means interposed bctween said arm and rod whereby the rod may be moved in one direction to actuate said switch, and when said arm is moved in another direction it will actuate the resistance cut out arm of the rheostat.

In testimony whereof I afiix my signature.

THOMAS A. MELVILLE.

Witnesses:

G. H. NEsBiT, ARCHER CRAIG, J r.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

